This invention relates generally to can tops for easy-opening cans and relates, more particularly, to the means and methods by which the can tops are produced.
Tabs for the can tops of easy-opening cans are made in commercially-available tab presses. One such press is the Minister P2-45 manufactured by the Minister Machine Company.
Tabs are commonly pressed in a die operation from a strip stock so that a formed tab has a smooth side and an opposite rough side. The smooth side of the tab is made in the bottom part of the die set. Thus, the rough side of the tab is made in the top part of the die set, and it is the rough side of the tab which faces downwardly in a completed can top.
The smooth side of a tab either cannot or has not been made by the upper portion of the tab die, and the invention with which this application is concerned proposes no change to that tab-forming process. As a strip of stock within which the tabs are formed are moved out of the tab press, the tabs are still attached in position in the strip, and the tabs are lying smooth side down and rough side up. (The smooth side of a tab is the side of the tab that faces upwardly when the top of a cola or beer can is viewed.)
The industry has long wanted a machine which combined the operation of making the tabs and attaching the tabs to the can tops. Such a machine would eliminate the labor costs involved in turning the tabs over following the formation of the tabs in the strip stock and the exit of the tabs from the tab die through chutes.
Heretofore, the tabs were punched out of the tab strip following the exit of the strip from the tab die, and the tabs moved in sequence out of the strip into the tab chutes, then to an individual who turned the tabs over. The tabs then traveled into fan end conversion press and were pressed on the can tops (or can ends).
The present invention eliminates the labor associated with the turning of the tabs over following the exit of the tabs from the tab die while not requiring that a single machine perform the combined operations of making the tab, turning the tab over and attaching the tab to the can top.
In particular, the present invention involves the step of permitting of the tab strip with the tabs attached thereto to move out of the tab press. Such can be effected in a Minister P-245 press (adapted to press tabs) by removing the punch and cutter at the front of the press. The camtrol box situated at the back of the press will roll the tab-formed strip along a designated path and if there is a need for another roller, a second Ferguson (i.e. commercially available) camtrol box can be installed. The tab-formed strip is then looped to turn the tabs over, and this looping occurs outside of the tab press. With the tabs turned over, the tab-formed strip can be passed underneath a tab punch and the tabs punched out into chutes. The punched tabs accumulate in chutes and are conveyed to the end conversion presses. Continuous operation can be had by adjusting the speeds of reciprocation of the tab press, tab punch and conversion presses so that the speeds are equal.
As an alternative to the looping of the strip, the tabs can be turned over by twisting the tab-formed strip after it has traveled out of the tab press.
The disclosure document with which this invention is concerned is no. 273384.